Numerous electronic devices, such as digital cameras, personal digital assistants, and internet appliances, utilize optoelectronic sensors. Optoelectronic sensors are semiconductor chips that are capable of electronically capturing visual information by converting light to electronic signals so that this information can be processed or viewed electronically. Optoelectronic devices, such as image sensors, charge coupled devices (CCDs), or other light sensitive sensors, require the sensors to have a “line of sight” through the package housing the optoelectronic sensors.
A conventional optoelectronic device usually encapsulates a semiconductor chip onto which the sensor is mounted in a package with a non-transparent molded resin or ceramic material, which prevents the encapsulated semiconductor chip from chemical or physical reaction with the external atmosphere as well as providing mechanical protection to avoid damage to the semiconductor chip from external sources. Typical packages include plastic or ceramic leaded or leadless packages, ball grid array (BGA) packages, and dual in line packages (DIP). However, for optoelectronic devices, the structure of the package for the device regardless of the type of package includes a glass cover mounted on the package so the optoelectronic sensor mounted in the package is capable of detecting light passing into the device through the glass cover.
Conventional packages for optoelectronic devices therefore consist of two pieces, a carrier substrate for the optoelectronic sensor and the glass cover to allow light to reach the optoelectronic sensor after encapsulation of the carrier substrate by either plastic or ceramic material.
Using conventional semiconductor device packaging with glass covers has several disadvantages. For example, the glass covers can separate from the plastic or ceramic packaging material resulting in the optoelectronic sensor being exposed to the external environment thereby eventually destroying the device.
Another problem is that moisture can enter the package causing condensation on the inside of the glass cover thus degrading the image capturing ability and quality of the device.
Additionally, the finished package consists of two pieces requiring the device to pass through the normal semiconductor wire bonding process, a cleaning process, and an assembly process to install the glass cover making the production cost of the conventional device high as well as requiring extra processing steps.
Therefore, there is need for a package for optoelectronic devices having a single piece construction with improved moisture resistance, lower cost, and higher reliability.
Solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.